Writing surface



M y 28, 1940- J. E. ARBERRY WRITING summon Filed March 25. 1939 INVENTOR (/fl/VEJE fie 65122 5 AT IORNEY Patented May 28, 1940 2,202,682 WRITING SURFACE l James E. Arberry, Pittsburgh, Pa., asslgnor to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania Application March 25, 1939, Serial No. 264,159

Claims. (01. 35-66) The present invention relates to media for reception of chalk markings and designs and it has particular relation to the provision of boards or tablets suitable for use as blackboards and 5 slates in schools, or for similar purposes.

One object of the invention is to provide a writing board or tablet which is light of weight, durable, and resistant to breakage.

A second object is to provide a board or tablet of the foregoing type, the surface of which is capable of receiving clear and distinct markings from crayons, which markingscan be easily and completely erased from the surface by means of felt, or similar erasers, without leaving objectlonal smudge.

A third object of the invention is to provide a board or tablet for receiving writing from crayons, which board presents a smooth, satiny surface of a desired color.

go These and other objects of the invention will be apparent from consideration of the following specification and the appended claims.

For the production of school or similar blackboards and slates capable of receiving markings u by chalk, crayons, slate pencils and the like, a large number of materials have been suggested. However, none of these is completely satisfactory from all view-points. Among the requisites of a good blackboard or slate are:

30 1. The ability readily to receive or take chalk marks. This has heretofore entailed the presence of a certain amount of gritty or abrasive material in the surface of the board.

2. Chalk marks must be easily erased with a 35 felt, or cloth. or other body of similar texture, without leaving permanent streaks ingrained in the surface and without leaving excessive and sharply defined smudges after the erasure.

3. The surface must be permanent and must 4" not tend to assume an objectionable polish which will not take chalk or crayon marks and which will be characterized by excessive reflections.

4. It is desirable that the board be of a pleasing color that harmonizes with the general motive 45 of the room in which it is employed. In recent years the tendency has been to employ lighter colors in school room decorations, in order to impart an atmosphere of light and cheerfulness to the room. Accordingly there has been a grow- 50 ing need for a. board of corresponding color.

Probably slabs of natural slate have, heretofore, more satisfactorily met the most essential requirements of a blackboard or school slate than any other material.

5 However, even it is objectional in certain respects. For example, it is heavy, cumbersome,

expensive and easily broken. Moreover, no choice of color is available. These slates are uniformly dark and therefore cannot be employed to increase the brilliancy of motive in a room. I Moreover, it will be obvious that the black surface is not suitable for use with many colors of crayons, or pencils.

The present invention involves the discovery that the smooth, satiny apparently gritless sur- 1 faces of oxidized or anodized plates or sheets of aluminum possesses the essential requisites of a blackboard or slate to a remarkable degree and in spite of the satiny finish will take chalk or crayon marks with ease. Moreover, the marks 15 can readily be expunged or erased without leaving objectionable streaks or smudges. Furthermore, the surface film is found to be exceedingly hard and resistant to abrasion so that objectional polishing does not occur even after prolonged use.

For a better understanding of the invention reference may now be had to the acompanying drawing in which Figure 1 is an elevational view of a blackboard embodying the invention.

Figure 2 is a fragmentary cross-sectional view of a portion of the board showing the different layers of materials embodied therein.

In the drawing like numerals refer to like parts.

The writing surface such as a blackboard l0 cemented or mounted upon a wall ll includes a plate or plaque l2 of aluminum of any desired thickness, grade and finish. This plate may comprise a simple plate of aluminum or a plate of steel or other material surfaced with aluminum by electrolysis or other method. The aluminum surface is provided with a smooth, satiny uniform aluminum oxide film l3 which may be formed thereupon by any conventional process of forming oxide films. The common method is the so-called anode processes in which the aluminum body is made the electrolytic anode in a bath of acid, such as chromic acid. The conventional Alumilite process is particularly satisfactory for the purpose. This process is well understood by those skilled in the art and need not be described in detail. A frame for the board is indicated at [4.

As previously indicated the oxide films upon the aluminum plates are smooth and satiny in feeling and appearance, which is quite different from slates and other common applicable materials, which in general must have a certain amount of grit or grain in order to make them a receptive to chalk or crayon markings. The marks may be expunged or erased with an ordinary felt, cloth, or other eraser without any objectional streaking or smudging. Although the film is comparatively thin it is none the less of great hardness and durability to abrasion. Therefore, it is capable of withstanding long and severe usage without failure. In event of ultimate failure it is an easy matter to remove the plates or plaques from the wall and reanodize them in order to provide a fresh working surface.

Oxide coatings upon slabs or plates of relatively pure aluminum are inherently of a silvery appearance and blend and harmonize most excellently with lighter shades of paint or varnish in a room. With such boards it is desirable to employ a black or colored crayon or chalk for marking purposes. By alloying the aluminum with silicon or other metal it is possible to form an oxide film upon the plate of darker hue which wfll be satisfactory for use with white chalks or crayons.

These oxide fihns upon aluminum plates are characterized by the ability to take dyes and pigments in order to provide practically any desired color for the film. It thus becomes possible by employing any of the conventional processes of dying to provide a board of any color. It is also possible to form designs in the aluminum film merely by applying a dye or pigment by printing or other processes thereof. Permanent guide lines constitute examples of such designs and are indicated at IS in the drawings. It is also possible to dye parts or all of the board to one shade but as score cards for card and similar games. or for practically any purpose where it is desirable to provide a tablet or plaque from which crayon or chalk marks can easily be expunged.

The form of the invention herein shown and described is merely illustrative; many modifications may be made therein without departure.

2. A wall blackboard for receiving chalk mark ings comprising a plate of aluminum having a 2 writing surface comprising an adherent anodic film of aluminum oxide, said film being capable of readily receiving crayon marks, such marks being easily erased therefrom by means of a felt or similar eraser.

3. A writing surface as defined in claim 1 in which the aluminum oxide film is impregnated with a dye of desired color.

4. A writing surface as defined in claim 1 in which the aluminum oxide film is impregnated with a dye to provide contrasting designs upon the surface thereof.

5. A blackboard for receiving crayon markings comprising a plate of aluminum having a frame andbeing secured upon a building wall and having a writing surface comprising an adherent anodic film of aluminum oxide, said film being capable of readily receiving crayon marks, such marks being easily erased by means of felt or similar erasers. 3

JAMES E. ARBERRY. 

